For inhibiting perspiration, the application to the skin of many different antiperspirant active compounds has been described in the literature. However, those compounds most widely employed in commercial products of the stick type for this purpose are basic aluminium halides, especially aluminium chlorohydrate which has an aluminium/chlorine molar ratio of about 2, and aluminium zirconium chlorohydrate complexes, including those combined with glycine, such as aluminium zirconium trichlorhydrex-GLY and aluminium zirconium tetrachlorhydrex-GLY. Especially popular are stick products in which the antiperspirant active is present as a powder in a finely divided form.
The effectiveness of an antiperspirant product can be assessed by subjecting human volunteers to thermal stress and gravimetric determination of axilla sweat.
By employing such a procedure, it can be shown that powder-containing stick antiperspirant products are more effective in reducing or eliminating the appearance of sweat at the skin surface than the so-called solution type antiperspirants, as the powder form allows for a greater amount of the antiperspirant active to be delivered to and deposited on the skin surface. Even so, powder antiperspirant products currently available on the market generally have limited efficacy in that a sweat reduction (as hereinafter defined) of no more than about 38% is achievable.
A further problem which can be experienced when using antiperspirant products of the powder-containing stick type is their tendency to be greasy and undesirably soft.
Just such a problem can occur with a powder-containing antiperspirant stick such as that described by Armour-Dial Inc. in their U.S. Pat. No. 4,126,679. This patent concerns a solid composition comprising 15 to 40% of an astringent metallic salt in powder form suspended in a matrix comprising 10 to 65% of volatile silicone and 15 to 70% of stearyl alcohol. Experience has shown, however, that this type of stick can be greasy and somewhat soft in use. Applicants have now discovered that by employing an anhydrous alcohol and a clay suspending agent with a much reduced level of volatile silicone, then a firmer, less greasy, stick is obtainable. Furthermore, the improved stick shows superior efficacy in use, in that sweat reduction (as hereinafter defined) of at least 45% is attainable.